KO______ FYI, I had no issues crossing the Polish border to Kaliningrad but was told I could not return to cross back as a USA passport holder, Not sure if thats still the case. So it might still be a one way for USA passports.
Himynameis KO______ do You know if US Passport holder with residency permits in the EU can come back?
KO______ Himynameis I dont know. I would assume if youre traveling with a USA passport this would affect you. You can do a little googling and try to find out more or just have a back up plan for leaving. Things are changing quickly at these borders so its hard to say 100%.